Laterally Deflectable Implant

ABSTRACT

A laterally deflectable asymmetric implant for implanting into a body may comprise a deflectable piece having distal and proximal ends and assuming a straightened insertion state. The backbone may abut or interconnect with said deflectable piece at the distal end of the deflectable piece. In a fully deflected state the implant may define an asymmetric shape, e.g. a D-shaped loop, defining an at least partially enclosed volume. The deflectable piece may comprise a sequence of segments interconnected at effective hinges. Longitudinal pressure applied to the proximal end of the deflectable piece (or applied to the backbone in an opposite direction) may cause relative longitudinal movement between the backbone and the proximal end of the deflectable piece and may generate outward horizontal movement of the deflectable piece away from the backbone. In one embodiment, the implant is implanted using lateral access into an anterior zone of a vertebra and deployed posteriorly.

FIELD AND BACKGROUND OF TIE INVENTION

The present invention generally relates to apparatus and methods forimplants, and more particularly to apparatus and methods for implantingdeflectable implants.

Minimally invasive and percutaneous subcutaneous procedures, which areperformed through a small orifice in the skin, limit the size of thesurgery tools and implants that are used. Hence it would be highlyadvantageous to develop implants that have small cross sections suchthat they can be inserted easily through a small orifice in the skin andbe formed into their final functional expanded shape at the intendedimplantation site in the body. It would be highly advantageous toprovide implants for spinal surgeries such as interbody fusion, motionpreservation and vertebral augmentation that may be inserted into thebody in minimally invasive procedures.

In addition, precise control over the location of an implant is vitallyimportant to the success or failure of a spinal surgery. Undesiredmovement of the implant after placement, imprecise placement, improperor imprecise opening, expanding or other forming of the implant afterinsertion can result in the implant not being precisely where the userintended the implant to be and imperfect fusion. Differences of amillimeter can change an otherwise successful surgery into anunsuccessful surgery. Many prior art methods and apparatuses have beendeveloped to control the exact placement and opening of implants, suchas those used in surgery, for example spinal surgery. There is acompelling need for an implant and a method of its implantation thatprovides the greatest clinical benefit and allows the user to haveprecise control over the insertion, deployment and follow-up positioningand use of the implant.

Furthermore, there is a need for alternative approaches to insertion ofimplants into the body, for example in spinal surgery, since approachesthrough the front have disadvantages, for example since they requiremoving vital organs.

SUMMARY OF THE PRESENT INVENTION

One aspect of the present invention is a laterally deflectable implantfor implanting into a body, comprising a deflectable piece having adistal end and a proximal end and assuming a straightened or lowcurvature insertion state for insertion into the body; and a backboneconfigured to interconnect with or abut the deflectable piece, thedeflectable piece in a fully deflected state defining, together withsaid backbone, an asymmetric loop wherein said asymmetric loop definesan at least partially enclosed volume, wherein longitudinal movement ofthe proximal and of the deflectable piece relative to at least a distalend of the backbone deflects the deflectable piece to the deflectedstate to form, with said backbone, the asymmetric loop, wherein theimplant in a deflected state is asymmetric such that the implant doesnot have an axis of symmetry parallel to the backbone.

A further aspect of the present invention is a method of implanting animplant into a body, comprising inserting the implant into an anteriorportion of the body using lateral access while the implant is in astraightened or low curvature state, the implant having a backbone and adeflectable piece meeting the backbone at a distal end of thedeflectable piece; and deploying the implant posteriorly by deflectingthe deflectable piece.

A still further aspect of the present invention is a method ofimplanting an implant into a body, comprising inserting the implant intothe body while the implant is in a straightened or low curvature state,the implant having a backbone and a deflectable piece, the backbonecomprising a beam; anchoring the implant by situating the backbone on acortical bone so that the backbone holds at least a majority of a loadon the implant; and guiding the deflectable piece by holding thebackbone stationary while applying longitudinal pressure to a proximalend of the deflectable piece so as to deflect the deflectable piece suchthat the deflectable piece together with the backbone form an asymmetricloop, the asymmetric loop defining an at least partially enclosedvolume.

A yet still further aspect of the present invention is a method ofimplanting an implant into a body, comprising inserting the implant intothe body while the implant is in a straightened or low curvature state,the implant having a backbone and a deflectable piece comprising asequence of segments interconnected at effective hinges; having a distalsegment of the sequence meet the backbone at a distal end of thedeflectable piece; and forming an asymmetric loop between the backboneand deflectable piece together by deflecting the deflectable piece suchthat a proximal end of the deflectable piece moves longitudinallyrelative to at least a distal end of the backbone and interconnects tothe backbone.

A still further aspect of the present invention, is a method ofimplanting implants into a body, comprising inserting into the body afirst laterally deflectable implant that has a first backbone and afirst deflectable piece while the first deflectable piece is in astraightened or low curvature insertion state; inserting into the body asecond laterally deflectable implant that has a second backbone and asecond deflectable piece while the second deflectable piece is in astraightened or low curvature insertion state and such that the firstand second backbones are substantially parallel; deflecting the firstand second laterally deflectable implants in opposite directions suchthat the first laterally deflectable implant defines a first asymmetricloop, said first asymmetric loop defines an at least partially enclosedvolume and such that the second laterally deflectable implant defines asecond asymmetric loop, said second asymmetric loop defines an at leastpartially enclosed volume.

A yet still further aspect of the present invention is a method ofdistracting intervertebral space between a first vertebra and a secondvertebra, comprising inserting an implant into a body while the implantis in a straightened or low curvature state, the implant having abackbone and a deflectable piece meeting the backbone; and generatingrelative longitudinal movement between a proximal end of the deflectablepiece and at least a distal end of the backbone so as to deflect thedeflectable piece and distract an intervertebral space between the firstand second vertebrae.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdrawings, descriptions and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 is an isometric view of an implant in a straightenedconfiguration for example prior to insertion into a body or afterinsertion but prior to deflection, in accordance with one embodiment ofthe present invention;

FIG. 2 is an isometric view of the implant of FIG. 1 in a deflectedstate, in accordance with one embodiment of the present invention.

FIG. 3 is a top view of an implant in a straightened configuration forexample prior to insertion into a body or after insertion, but prior todeflection, in accordance with one embodiment of the present invention;

FIG. 4 is a top view of the implant of FIG. 3 in a deflected state, inaccordance with one embodiment of the present invention;

FIG. 5A is an isometric view from the top of a deployer on a holder, inaccordance with one embodiment of the present invention:

FIG. 5B is an isometric view from the bottom of a deployer on a bolder,in accordance with one embodiment of the present invention;

FIG. 6 is an isometric view of a holder, in accordance with oneembodiment of the present invention;

FIG. 7A is a top view of an implant showing a locking mechanism, inaccordance with one embodiment of the present invention;

FIG. 7B is a top view as in FIG. 7A with a tooth in a slot in lockedposition, in accordance with one embodiment of the present invention;

FIG. 7C is a top view as in FIG. 7A with a tooth locked in a secondlocking position, in accordance with one embodiment of the presentinvention;

FIG. 8 is a front view of a straight beam used as a backbone for animplant and having anchoring ridges on a top and bottom surface, inaccordance with one embodiment of the present invention;

FIG. 9 is an end view of an implant including a backbone and adeflectable piece, in accordance with one embodiment of the presentinvention;

FIG. 10 is an isometric view of a segment of a deflectable piece showinga curved exterior, in accordance with one embodiment of the presentinvention;

FIG. 11 is a top view of a vertebra showing the vertebral body dividedinto four equal zones;

FIG. 12 is a top view of an implant positioned over zone two of avertebral body by lateral access, the implant in a straightenedconfiguration and held by a holder; in accordance with one embodiment ofthe present invention:

FIG. 13 is a top view of the implant of FIG. 12 wherein the implantbackbone is positioned over zone two of the vertebral body but thedeflectable piece has been deflected into zone three by the deployer onthe holder, in accordance with one embodiment of the present invention;

FIG. 14 is a top view of an implant positioned on the vertebral body asin FIG. 13, but with the holder and deployer having already beenseparated and removed from the implant, in accordance with oneembodiment of the present invention;

FIG. 15 is an isometric view of an implant with a deflected sequence ofsegments in the deflectable piece wherein the backbone is flat;

FIG. 16 is a flow chart showing a method in accordance with oneembodiment of the present invention:

FIG. 17 is a flow chart showing a further method in accordance with oneembodiment of the present invention:

FIG. 18 is a flow chart showing a still further method in accordancewith one embodiment of the present invention;

FIG. 19 is a flow chart showing a further method in accordance with oneembodiment of the present invention;

FIG. 20 is a flow chart showing a still further method in accordancewith one embodiment of the present invention;

FIG. 21 shows isometric views of an implant and abiocompatible-material-delivery device, in accordance with oneembodiment of a system of the present invention:

FIG. 22A shows a laterally deflectable implant inserted through a TL IFapproach, in accordance with one embodiment of the present invention;

FIG. 22B shows two laterally deflectable asymmetric implants alongsideone another resulting from a PLIF insertion approach, in accordance withone embodiment of the present invention;

FIGS. 23A,B are side views of an implant, holder and deployereffectuating vertical distraction of the intervertebral space betweenendplates, in accordance with one embodiment of the present invention;

FIGS. 24A-B are top isometric views of an implant with two sequences ofsegments each with adjustable backbones, before and after deflection, inaccordance with one embodiment of the present invention;

FIGS. 24C-E are top isometric views of an implant whose deflectablepiece has two sequences of segments each deflected separately andindependently using adjustable length backbones, in accordance with oneembodiment of the present invention; and

FIG. 25A is an isometric view of an implant with an adjustable lengthbackbone in a straightened state, m accordance with one embodiment ofthe present invention;

FIG. 25B is an isometric view of an implant with an adjustable lengthbackbone after deflection, in accordance with one embodiment of thepresent invention;

FIG. 26A is an isometric view of an implant whose undeflecteddeflectable piece includes side panels useful for vertical distraction,in accordance with one embodiment of the present invention;

FIG. 26B is a vertical sectional view of the implant of FIG. 26A, inaccordance with one embodiment of the present invention;

FIG. 26C is an isometric view of the implant of FIG. 26A afterdeflection of the deflectable piece, in accordance with one embodimentof the present invention;

FIG. 26D is a vertical sectional view of the implant as shown in FIG.26C, in accordance with embodiment of the present invention:

FIG. 27A is an isometric view of an implant, deployment tube and holdershaft, in a straight configuration before deflection, in accordance withone embodiment of the present invention;

FIG. 27B is an isometric view of the implant, deployment tube and holdershaft of FIG. 27A after deflection, in accordance with one embodiment ofthe present invention;

FIG. 27C is an isometric view of the implant, detachment tube and holdershaft of FIG. 27A shown from an opposite side and before deflection, inaccordance with one embodiment of the present invention:

FIG. 27D is an isometric view of the implant, deployment rube and holdershaft of FIG. 27C after deflection, in accordance with one embodiment ofthe present invention

FIG. 27E is a vertical sectional view of the implant, deployment tubeand holder shaft of FIG. 27C with the implant in straightenedconfiguration, in accordance with one embodiment of the presentinvention;

FIG. 27F is a vertical sectional view of the implant, deployment tubeand holder shaft of FIG. 27C with the implant in partially deflectedstate, in accordance with one embodiment of the present invention.

FIG. 27G is a vertical sectional view of the implant, deployment tubeand holder shaft of FIG. 27C with the implant in partially deflectedstate, in accordance with one embodiment of the present invention;

FIG. 27H is a vertical sectional view similar to FIG. 27G except withthe deployment tube detached, in accordance with one embodiment of thepresent invention;

FIG. 27I is a vertical sectional view similar to FIG. 27G except withthe deployment tube detached and the holder shaft also removed, inaccordance with one embodiment of the present invention;

FIG. 27J is an isometric view of the deflected implant without thedeployment tube or holder shaft and revealing the engagement teeth atthe rear of the threaded tube; and

FIG. 27K is an isometric view of the end of a disconnected deploymenttube showing its engagement teeth, in accordance with one embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplatedmodes of carrying out the invention. The description is not to be takenin a limiting sense, but is made merely for the purpose of illustratingthe general principles of the invention, since the scope of theinvention is best defined by the appended claims.

The present invention generally provides a method and apparatus forlaterally deflectable implants, and systems and methods for implantingdeflectable implants having a loop structure in a human or animal bodywhich may be asymmetric, for example D-shaped, in a deflected state. Theimplant may during its delivery assume a straightened or low-curvatureconfiguration to facilitate delivery via a minimally invasive procedure.The implant may have a deflectable piece having a distal end and aproximal end and may have a backbone configured to meet (i.e. to abut orinterconnect with) the distal end or the proximal end. The deflectablepiece may be comprised of a sequence of two or more segments that may beinterconnected to one another by effective hinges. The effective hingesmay be integral hinges such as lateral cut-outs that close upondeflection or the effective hinges may be actual mechanical hingesbetween the segments. The deflectable piece may be interconnected withthe backbone at the distal and and/or al the proximal end of thedeflectable piece. If the deflectable piece is connected to the backboneat the distal end of the deflectable piece prior to deflection, thenupon deflection, the deflectable piece may also be interconnected withsaid backbone at the proximal end of the deflectable piece. In adeflected state, for example a fully deflected state, the deflectablepiece may define, together with said backbone, an asymmetric loop thatdefines an at least partially enclosed volume. To deflect, eitherlongitudinal pressure may be applied to the proximal end of thedeflectable piece or to the backbone so as to generate relativelongitudinal movement between the proximal end and at least a distal endof the backbone. This may generate an outward horizontal movement of atleast a central portion of the deflectable piece away from the backbone.The implant may be asymmetric about an axis defined by the direction ofinsertion and running from the proximal and distal ends and situatedbetween the backbone and the deflectable piece.

In certain embodiments, the implant is arranged to open towards one sideof the axis defined by the direction of insertion, and may beasymmetrical about that axis, as will be exemplified below.

In the context of the present description and claims, the word “loop” isused to refer to any structure in which following along the contiguousstructure can lead back to the starting point while encircling at leastone point lying outside the device, except that there may be a gapbetween a proximal end (or a distal end) of the deflectable piece andthe backbone, most often the proximal end (or the distal end) of thebackbone. Typically, and in one preferred embodiment, any such gap doesnot exceed 10% of a length of the backbone (in the case of telescopingbackbones, the length of the backbone when the implant is fullydeflected). In other preferred embodiments, the loop is called amodified loop or asymmetric modified loop and, if there is a gap betweena proximal end (or a distal end) of the deflectable piece and thebackbone, any such gap does not exceed 15% or 20% or 25% or 50% or 75%of such length, depending upon the embodiment. In the event a modifiedloop is used, such modified loop may be used in conjunction with anyother compatible feature or step of the present invention. In certaincases, completion of the loop may be in the form of a sliding joint. Theword “loop” does not carry any implication of a circular or smoothshape, although such shapes are in certain cases preferredimplementations of the loop structure when open. In still otherpreferred embodiments, the word “strict loop” is used to refer to anystructure in which following along the contiguous structure can leadback to the starting point while encircling at least one point lyingoutside the device. Embodiments featuring strict loops may be used inconjunction with any other compatible feature or step of the presentinvention

The term “low curvature” insertion state refers to a configuration ofthe deflectable piece of the implant in which at least one dimension ofthe deflectable piece, for example the width, other than thelongitudinal dimension (i.e. the direction of elongation) of theimplant, is significantly reduced, typically to less than 50% (and insome other preferred embodiments to less than 30% or in other preferredembodiments to less than 10%) of the corresponding dimension in itsfully deflected state, in order to facilitate delivery through a smallorifice. Note that a “straightened configuration” would not be reducedto 0% of the corresponding dimension due to the inherent width of thedeflectable piece, even when not deflected at all. In the presentcontext, moreover, the implant, which may comprise the deflectable pieceand the backbone together, has a “low-profile” configuration in whichpreferably two transverse dimensions are small compared to the directionof elongation of the implant, for easy delivery in a minimally invasiveprocedure, and the implant device opens up in one or two transversedimensions when deployed.

Particularly preferred but non-limiting examples of implementationsinclude intervertebral implants for supplementing, supporting orreplacing an intervertebral disc as part of a fusion procedure or as amotion preserving implant, and intravertebral implants for supporting orrestoring a vertebral body. The deflectable implants may include asequence of segments interconnected with effective hinges (such asconventional hinges or integral hinges) or may be formed with at leastan elongated side without clearly distinguished segments.

According to certain embodiments of the present invention, thedeflectable piece may comprise a sequence of segments. While a“sequence” means at least two segments, more preferably the sequenceincludes at least three, and in many preferred cases four or moresegments. The segments may be interconnected at effective hinges, thesequence assuming a straightened or low curvature insertion state forinsertion into the body, and being deflectable to a deflected state, forexample a fully deflected state, that may be defined by abutment ofabutment features of adjacent of the segments.

According to certain embodiments of the present invention, an implantfor interbody fusion is disclosed. The implant may be deflectable to adeflected loop, for example a fully deflected loop, inside the body,where the loop defines an enclosed volume (or an at least partiallyenclosed volume, for example if the loop is not a strict loop and has agap) with the upper and lower surfaces of the body. The implant forinterbody fusion further includes at least one opening in one or both ofthe elongated sides allowing access to the enclosed volume wherein theat least one opening is used to fill the enclosed volume in the fullydeflected loop state with biocompatible filling materials for interbodyfusion.

According to certain embodiments of the present invention, an implantfor motion preservation is disclosed. The implant is deflectable to adeflected loop, for example a fully deflected loop, inside the body,where the loop defines an enclosed volume (or an at least partiallyenclosed volume, for example if the loop is not a strict loop and has agap) with the upper and lower surfaces of the body. The implant forinterbody fusion further includes at least one opening in one or both ofthe elongated sides allowing access to the enclosed volume wherein theat least one opening is used to fill the enclosed volume in the fullydeflected loop state with inert biocompatible filling materialsapplicable for motion preservation.

According to certain embodiments of the present invention, an implantsystem for implanting implants described herein above is disclosed. Theimplant system includes further an injector containing filling materialssuch as but not limited to biocompatible materials, bone grafts, bonechips, bone-growth enhancing agents for interbody fusion or inertfilling materials, such as cement for interbody fusion or forstabilizing compression fractures, or other nucleus reinforcement orreplacement material for motion preservation.

In contrast to prior art implants, which may be straight or circular orof other various shapes, the present implant may be asymmetric, such asD-shaped and may, in a deflected state, comprise an asymmetric loop thatmay define an at least partially enclosed volume. For example, theimplant of the present invention may be comprised of (i) a deflectablepiece and (ii) a backbone that is not deflectable or at least notnormally deflected. In still further contrast to prior art implants, thedeflectable piece may be comprised of a sequence of segments that may beinterconnected at effective hinges. In some preferred embodiments, andin contrast to prior art implants, the effective hinges may be lateralcut-outs, for example triangular lateral cut-outs that may close upondeflection. The deflected state, for example the fully deflected state,may be defined by abutment of abutment features (for example surfaces,which may also be called abutment surfaces) of adjacent segments of thesequence. In further contrast to prior art implants, in which theimplant opens using a tensioning element or a mechanical linkage, theimplant of the present implant may open upon longitudinal pressureapplied either to a proximal end of the deflectable piece or to thebackbone to generate relative longitudinal movement between at least adistal end of the backbone and the proximal end of the deflectablepiece. In contrast to the manner of opening prior art implants, thisapplication of longitudinal pressure may generate relative longitudinalmovement between the proximal end of the deflectable piece and at leasta distal end of the backbone and may generate an outward horizontalmovement (transverse to the longitudinal movement and in a preferredembodiment along a plane of or substantially parallel to anintervertebral disc) of at least a central portion of the deflectablepiece away from the backbone, thereby deflecting the deflectable pieceto the deflected state to form, with said backbone, an asymmetric loop,such as a D-shaped loop. This may be accomplished in part because incontrast to prior an implants, in which a proximal end of a deflectableportion is either free or interconnected, the implant of the presentinvention may have a deflectable piece that is free on its proximal endprior to insertion and prior to and during at least a portion of itsdeflection but meeting (abutting or interconnected to) the backbone at adistal end after the deflection, or at least during the deflection. Infurther contrast to prior art implants, which may be symmetric and mayexpand symmetrically after insertion, the implant of the presentinvention may be asymmetric along an axis defined by a direction ofinsertion and running between a proximal and distal end of thedeflectable piece and situated between the backbone and deflectablepiece. Accordingly, the implant of the present invention may expandasymmetrically by deflection of the deflectable piece on only one sideof the axis. In further contrast to prior art implants, the height ofthe backbone may in certain preferred embodiments be at least as greatas the deflectable piece (or, in other preferred embodiments, at leastas great as a proximal segment of the delectable piece). In stillfarther contrast to prior art implants, at least one segment may have acurved exterior and/or may have an elliptical and/or anatomically shapedcross-section, at least at a top, bottom and at least one side (i.e. theat least one segment has a cross-section that corresponds to an ellipseat a top, a bottom and at least one side of the at least one segment).Furthermore, in contrast to method of implanting in the prior art, themethod of implanting of the present invention may involve inserting theimplant laterally, which has clinical benefits, such us avoiding thenerve root, avoiding major blood vessels, eliminating the need for afacetectomy, and allowing very large implants to be implanted to affordgreater stability. In further contrast to prior art implantationmethods, the method of implanting of the preset invention in certainpreferred embodiments may involve initially inserting the implant intoan anterior portion of a spine and then deployed posteriorly. Forexample, the implant may be laterally inserted into zone two of thespinal column and then deflected into zone three and/or zone four. Inother preferred embodiments, the method of the present invention mayinvolve inserting posteriorly and then deflecting anteriorly. In furthercontrast to prior art methods, the method of the present invention mayinvolve setting an initial position of the backbone so as to pre-definethe final position of the implant. For example, the backbone may be heldstationary during deflection of the deflectable piece. In furthercontrast to prior art methods of implantation, the backbone may beconfigured to hold at least a majority of the load of the implant andmay be configured to be emplaced under or between cortical bone toreceive the impact of such load. For example, the backbone may be asolid beam whose width may be at least half the height of the backbone(or in other preferred embodiments, at least two-thirds or at leastthree-quarters or in some preferred embodiments between one times theheight and one and a half times the height or in other preferredembodiments between one half times and one and one half times theheight). In still further contrast to prior art implants and methods,one method of the present invention may involve inserting two laterallydeflectable implants so that their backbones may be substantiallyparallel and may be alongside one another and then deflecting each ofthe implants in opposite lateral directions to define two asymmetricloops. In further contrast to the prior art implantation methods whereindeflection of the implant is lateral or radial, one embodiment of thepresent invention is a method of implantation involving inserting theimplant in a straightened or low curvature state and deflectingvertically to distract an intervertebral space between two discs of aspine. In still further contrast to implantation methods of the priorart, one embodiment of the present invention may involve separatelydeflecting different sequences of interconnected segments of thedeflectable piece of the implant, wherein the different sequencescombines comprise the deflectable piece. One application of this is todeflect the implant so as to form a “B” shaped implant. In still furtherto prior art implant that deflect, the implant of the present inventionmay utilize a backbone that telescopes to adjust its length and therebygenerate the relative longitudinal movement between the proximal end ofthe deflectable piece and at least a distal end of the backbone.

The principles and operation of an apparatus and method for a laterallydeflectable implant according to the present invention may be betterunderstood with reference to the drawings and the accompanyingdescription.

As shown in FIG. 1, a laterally deflectable implant may be in astraightened or low curvature insertion state for insertion into thebody. In this case, the implant 10 is in a straightened insertion state.Implant 10 may comprise a deflectable piece 20 that may have a distalend 22 and a proximal end 24 and a backbone 30 that may be configured tomeet (i.e. abut or interconnect with) deflectable piece 20, for exampleat the distal end 22 of deflectable piece 20 (or at the proximal end24). According to certain embodiments, a deflectable piece 20 may beformed of a single body of flexible material and may have at least afirst and a second elongated side.

Backbone 30 is typically generally straight and normally is notconfigured to deflect.

Backbone 30 may abut or interconnect with deflectable piece at a distalend 36 of backbone 30 (or at a different portion of backbone 30).Typically this positioning may be such that deflectable piece 20 isinterconnected with backbone 30 or else deflectable piece 20 may merelyabut backbone 30. If the backbone and deflectable piece are abuttingwithout an interconnection, this may still allow application oflongitudinal pressure against deflectable piece 20 or backbone 30 tocause relative longitudinal movement of proximal end 24 relative to atleast a distal c d 36 of backbone 30 causing deflection of deflectablepiece 20. “Distal end” of backbone 30 is defined to mean the last 10% ofbackbone 30. In other preferred embodiments, the relative longitudinalmovement of proximal end 24 is relative to at least a “distal part” ofthe backbone, which may be the last 5%, or in other preferredembodiments the last 15%, or the last quarter, or the last third, or thelast 40%, or in still other preferred embodiments the region ofattachment of the distal segment to the backbone. In some preferredembodiments, the proximal end 24 of deflectable piece 20 moveslongitudinally relative to the entire backbone 30 (particularly when thebackbone is not an adjustable length backbone).

In some preferred embodiments, deflectable piece 20 and backbone 30 areinterconnected even before insertion of the implant 10 into the body. Inother preferred embodiments, backbone 30 may be inserted into the bodyfirst and then deflectable piece 20 may be inserted so as tointerconnect along a rail on backbone 30, for example sliding along therail longitudinally until deflectable piece 20 abuts a tip 37 ofbackbone 30. Deflectable piece 20 may be hingedly interconnected withbackbone 30 at distal end 22 of the deflectable piece, as shown in FIG.2. Note that when deflectable piece 30 is in a straightened (or lowcurvature) configuration, implant 10 is said to also be in astraightened (or low curvature) configuration.

When deflectable piece 20 is in its straightened or low curvatureconfiguration, backbone 30 may extend alongside deflectable piece 20, asshown in FIG. 1. When deflectable piece 20 is in its deflected state,backbone 30 may be alongside only the ends 22, 24 of deflectable piece20 and backbone 30 may extend from the distal end 22 of the deflectablepiece 20 to the proximal end 24 thereof.

As shown in FIG. 2, in addition to abutting or interconnecting withbackbone at one end such as a distal end of backbone, deflectable piece20 in a deflected state, for example after insertion, may also beinterconnected (for example hingedly) with said backbone 30 at theproximal end 24 of deflectable piece 20 and backbone 30 may then extendbetween the distal end 22 and the point of interconnection which may beproximal end 24 of the deflectable piece 20. In some preferredembodiments (not including, for example, embodiments in which thebackbone 30 has telescoping portions), the proximal end 24 ofdeflectable piece 20 is not in contact with the backbone prior todeflection of the deflectable piece 20.

When deflected, for example when fully deflected, the deflectable piece20 may define, together with backbone 30, an asymmetric loop 39 (orasymmetric modified loop), which may be f-shaped. D-shaped loop 39 maydefine an at least partially enclosed volume 39V. When the deflectablepiece 20 of implant 10 is fully deflected, the asymmetric loop may insome embodiments have a toroidal shape, for example a ring toroid or anoval toroid (or in other embodiments a toroidal polyhedron). Theinterconnection between proximal end 24 of deflectable piece 20 andbackbone 30 may typically occur at or near the completion of thedeflection, although this is not a requirement or a limitation ofimplant 10. In addition, in some preferred embodiments, asymmetric loop39 may not be fully closed—for example even in a fully deflected statethere may be a gap between backbone 30 and the proximal end 24 ofdeflectable piece 20. Typically, any such gap does not exceed 10% of alength of the backbone (in the case of telescoping backbones, the lengthof the backbone when the implant is fully deflected) and in otherpreferred embodiments, does not exceed 15% or 20% or 25% of such length.

As shown in FIG. 2, deflectable piece 20 may comprise a sequence 41 ofsegments 40, for example segments 40 a, 40 b and 40 c. “Segments 40” isused to refer in general to the segments 40 a, 40 h, 40 c, etc. Segments40 may be interconnected with one another at effective hinges 47 forexample effective hinges 47 a, 47 b, etc. As shown in FIG. 3, theeffective hinges 47 may be comprised of lateral cut-outs 48 a, 48 b, 48c between segments 40 a, 40 b, 40 c and 40 d. The lateral cut-outs 48a-c may be triangular or substantially triangular and as shown in FIG. 4may close upon deflection. In some preferred embodiments, the sequence41 of segments 40 is deflectable to a deflected state, for example afully deflected stale, defined at least partially by abutment ofabutment features 43 (for example surfaces) of adjacent segments of thesequence 41 of segments 40. The abutment features 43 may function as alimiter feature to prevent rotation about the hinges beyond thedesirable range in either clockwise or counterclockwise direction(s). Inembodiments without cut-outs, another limiting feature may be used, forexample a limiter built-in to the hinge (not shown). In order to improverobustness of the torque of the segments 40, the segments 40 may beinterconnected to one another by interdigitation, for exampleinterlocking fingers.

If deflectable piece 20 is comprised of segments 40, then proximal end24 of deflectable piece 20 is a part of the most proximal segment 40 a.For clarity, as shown in FIG. 2, middle segment 40 b may have a sidesurface 25.

In order for the deflectable piece 20 to change from the straightened orlow curvature state shown in FIG. 1 to the deflected state, for examplethe fully deflected state, shown in FIG. 2, longitudinal pressure may beapplied to the proximal end 24 of the deflectable piece 20. As shown inFIGS. 5A-5B, this may be accomplished with a deployer or “pusher”component 60 which may be a separate component or may be located on aholder 50 (FIG. 6). Application of the longitudinal pressure maygenerate relative longitudinal movement between the proximal end 24 andbackbone 30 to cause deflection of deflectable piece 20. In addition,the longitudinal pressure may generate an outward horizontal (lateral)movement (transverse to the longitudinal movement and, in a preferredembodiment, along a plane of or substantially parallel to anintervertebral disc) of at least a portion 28 of the deflectable piece20 away from the backbone 30, thereby deflecting the deflectable piece20 to the deflected state to form the asymmetric loop 39 together withbackbone 30. The portion 28 referred to may be a central portion ofdeflectable piece 20, which in this context is not in any way limited toa portion that is right in the middle of deflectable piece 20 ornecessarily in a middle segment 40 of the deflectable piece 20. Rather,the central portion is any portion that is not at the very remote end atthe distal end 22 and not at the very remote end at the proximal end 24of deflectable piece 20.

If deflectable piece 20 is not made up of segments, then the centralportion 28 may be thought of as a bow expanding outward with the endsfixed. In some embodiments, the outward expansion, i.e. the deflectionof the deflectable piece 20, may be centered at a point that is not atthe midpoint between the distal and proximal ends 22, 24. The deflectionof deflectable piece 20 allows the deflectable piece together with thebackbone to form a loop, and in particular a D-shaped loop.

Instead of longitudinal pressure applied against proximal end 24, forexample to push proximal end 24, there may be longitudinal pressureapplied to backbone 30, for example to pull a distal end 32 of backbone30. In general, in either case, relative longitudinal movement betweenbackbone 30 and proximal end 24 of deflectable piece 20 may be generatedto deflect deflectable piece 20 to its deflected state and thereby formasymmetric loop 39.

As shown in FIGS. 25A-25B, backbone 30 may be adjustable in length.Accordingly, in embodiments in which the length of backbone 30 isadjustable and this adjustability is utilized to generate relativelongitudinal movement between a proximal end of deflectable piece 20 andat least a distal end of the backbone, the proximal end 24 ofdeflectable piece 20 may be in contact with backbone 30 (and in tact maybe attached to backbone 30) even before deflection of deflectable piece20. For example, backbone 30 may include a first telescoping portion 88a of the backbone 30 that telescopes into or with a second telescopingportion 88 b of backbone 30. As seen in FIG. 25B, the proximal end 24 ofdeflectable piece 20 may be attached to first telescoping portion 88 aof the backbone such that deflection of the deflectable piece 20 isactuated by moving the first telescoping portion 88 a relative to thesecond telescoping portion 88 b of backbone 30. Although the number oftelescoping portions in backbone 30 has been described as two, thisnumber can also be greater than two, such as three, four or highernumbers. First and second telescoping portions 88 a, 88 b may belinearly aligned (i.e. collinear) as part of backbone 30. Furthermore,in a preferred embodiment, when first and second telescoping portions 88a. 88 b telescope within one another, they do so without one telescopingportion sticking out the other longitudinal end of the other telescopingportion. In preferred embodiments, first and second telescoping portionsmaintain substantially equal heights even when telescoping within oneanother (since for example the outer surfaces of each may notparticipate in the telescoping).

In FIGS. 24A-E, the deflectable piece 20 is comprised of a firstsequence of segments associated with first and second telescopingportions 88 a, 88 b of the backbone 30 and is comprised of a secondsequence 41 of segments associated with third and fourth telescopingportions 88 a, 88 b of the backbone.

As shown by FIGS. 27A-K, the present invention may utilize in anysuitable embodiment of implant 10 (or method or assembly) an implant 10having an adjustable-in-length backbone 30 in which axial movementbetween parts of the backbone 30 is accompanied by relative rotation ofthe parts. The backbone may comprise a rotatable element 93 and anannular element 95, the rotatable element attached to or abutting thedeflectable piece and configured to move longitudinally by rotatinglyengaging the annular element. Rotatable element 93 may be a tube 93 suchas a threaded tube 93 that is threaded at a distal portion 93 a thereof,such as at a tip 93 a. The annular element 95 may be a threaded nut 95,such as a female threaded nut, that receives the rotational movement ofthe threaded tube. Threaded nut 95 may be fixed. This embodimentresembles telescoping but differs from “telescoping” (which typicallyinvolves axial movement of a part within a part without accompanyingrotation of these parts) since here, besides longitudinal/axial movementof a part of backbone 30 within another part, there may also be rotationof at least one part of the backbone 30, and typically rotationalengagement or relative rotation between that one part and at least oneother part of the backbone 30.

As shown in FIG. 27A, a pin 96 may be used to connect a segment 40 a(which in the view of FIG. 27A is a distal segment) of deflectable piece20 to backbone 30. Furthermore, a proximal axis/axle 97 may be used toattach a proximal end of rotatable element 93 to deflectable piece 20,for example to proximal segment 40 c, or in general to a proximal pan ofdeflectable piece 20. Since the rotatable element is attached to (orabutting) the proximal part of the deflectable piece, the deflectablepiece may move longitudinally relative to at least a distal end of thebackbone when the rotatable piece 93 advances longitudinally withrespect to annular element 95.

An implant assembly 1000 may include an implant 10 with this kind ofadjustable-in-length backbone 30 and may further include a holder shaft92 running through the backbone 30, the holder shaft 92 including aholder shaft tail 92 a jutting out a proximal end of the implant. Suchan assembly may further comprise a deployment tube 91 enclosing theholder shaft tail 92 a and being operatively engage d to the rotatableelement 93 to rotate the rotatable element 93.

FIG. 27E is a vertical sectional view of an implant 10 whose deflectablepiece 20 comprises segments 40 a. 40 b. 40 c and whose backbonecomprises a threaded tube 93 and a female threaded nut 95. In practice,a user may first insert a holder shaft 92 through implant 10, forexample through the entire length of implant 10. The holder shaft 92 mayconnect to a distal tip of implant 10. The holder shaft 92 may have aholder shaft tail 92 a that sticks out the proximal end of implant 10and may attach to a handle (see FIGS. 5A-6). The user may then attach adeployment tube 91 over holder shaft tail 92 a such that engagementteeth 91 b of the deployment tube 91 mate with engagement teeth 93 b atthe proximal end of threaded tube 93, as seen in FIGS. 27G-27K,especially FIGS. 27J-27K.

It should be understood that the embodiments in which the length of thebackbone 30 is adjustable may have any of the other structural featuresof implant 10 described herein, and may be used in any of the methodsdescribed below, although as indicated such embodiments typically wouldnot employ a deflectable piece 20 whose proximal end 24 is not incontact with the backbone 30 of the implant prior to deflection.

Furthermore, in this patent application in general, the structuralfeatures and method steps described in the context of one embodiment, orillustrated in a drawing of one embodiment, are not limited to thatembodiment and may be adapted to any of the implants or methodsdescribed herein, unless otherwise indicated.

Asymmetric loop 39 may assume other shapes besides a D-shape such asrectangular, trapezoidal, triangular and B-shaped (i.e. two D-shapedimplants with backbones that are substantially aligned). Moreover, incertain preferred embodiments, there may be two implants lined up suchthat the backbones 30 of each implant are substantially parallel oralongside one another such that the two implants together form twoD-shapes. Moreover, “D-shape” does not require a perfect D. There couldbe a slight projection of backbone 30 beyond where backbone 30 meetsdeflectable piece 20 on the proximal and/or distal end.

As seen from FIG. 1, proximal end 24 of deflectable piece 20 may be afree proximal end during insertion of the implant, i.e. not connected tobackbone 30 or to another element of implant or of holder 50 or deployer60. Proximal end 24 may be free proximal end during at least a majorityof the deflection of the deflectable piece, the majority measured byreference to how great of an outward horizontal distance the deflectablepiece 20 has moved. In some preferred embodiments, proximal end 24 isattached to backbone 30 at or near the end of the application oflongitudinal pressure by deployer 60. Accordingly, proximal end 24 maybe free other than in the deflected state, for example the fullydeflected state, of the deflectable piece 20. In other preferredembodiments, however, proximal end 24 may be free even in the fullydeflected state. In some preferred embodiments, for example as shown inFIG. 1, the proximal end 24 of deflectable piece 20 is not in contactwith backbone 30 prior to deflection of deflectable piece 20.

As shown in FIG. 2 and FIG. 7B, in some preferred embodiments, aproximal end 24 of deflectable piece 20 may interconnect with thebackbone at a proximal end of backbone 30, for example at theculmination of the deflection of deflectable piece 20. Typically,backbone 30 is not configured to deflect and is normally rigid.Nonetheless, in order to facilitate locking or other engagement todeflectable piece 20, backbone 30 could for example have a slit allowingat least a portion of backbone 30 to bend, for example up to 15 or 20rotational degrees of the longitudinal axis of backbone 30 (as measuredfrom a distal to a proximal end of backbone 30), so as to facilitateengagement of a proximal end of deflectable piece 20 to backbone 30, forexample at the culmination of the deflection of deflectable piece 20. Inthis version, backbone 30 would resume its original shape after theengagement with deflectable piece 20.

As can be seen front FIGS. 1-2, since backbone 30 and deflectable piece20 are not identical, implant 10 may be asymmetric about a longitudinalaxis running from one end of deflectable piece 20 to the other (forexample in a direction of insertion of the implant 10) when the implant10 is in a deflected state. The asymmetry may be particularly pronouncedfor example when the longitudinal axis is situated between thedeflectable piece 20 and the backbone 30, for example where thebackbone, deflectable piece and longitudinal axis are all onsubstantially one plane. The implant (and the loop) in a deflected statemay be asymmetric such that the implant (and the loop) does not have anaxis of symmetry parallel to the backbone 30.

The implant 10, including the backbone 30 and deflectable piece 20, maybe made of any suitable biocompatible material (i.e. titanium, PEEK,shape memory alloy, steel, cobalt-chrome alloy etc.). The cross-sectionof implant 10 may be straight, as shown in FIGS. 1-2, or may be angledto create a lordotic angle between the vertebral bodies. Optionally, thelordotic angle may be created by having segments (of deflectable piece20) of varying or graduated heights within the same implant 10.

An end 32 (FIG. 2) of backbone 30 (for example proximal end 32) mayinterface with a holder instrument 50 (see FIG. 6 and FIG. 12) thatholds implant 10. As seen from FIG. 6, holder 50 may be an elongatedinstrument and may be made of metals, polymers or a combination ofmaterials. One end 52 (i.e. a distal end) of holder 50 may have one ormore such interfaces with functions such as anti-rotation of implantdevice 10 on the instrument 50, quick connect/quick release or otherattachment/release method of the implant 10. For example, theanti-rotation feature 32 a on the proximal end 32 of backbone 32 mayinterface with an anti-rotation feature on the distal end of holder 50.There may be separate features for attachment and release of implant 10from the holder instrument 50. There may be a feature designed tominimize user error in attaching implant device 10 to the holder 50. Theinterface features may appear on corresponding ends of the holder 50 andbackbone 30. The proximal end 54 of holder 50 may have a surface forpushing or tapping to effectuate advancing the implant 10 into thedesired location in the body. The interface on distal end 52 may beconnected to a component(s) 66 (i.e. a knob, button, dial, handle, etc.)on the proximal end 54 so that the user can perform the necessaryfunctions to the implant 10 (connect, deploy, disconnect, etc.).

As shown in FIG. 5A, deployer 60 may have a component for aligning ordirecting a biocompatible material such as bone into the window 29 ofdeflectable piece 20 or of a segment(s) of the sequence 41 of segments40. Deployer 60 may be integrally formed as part of the holder 50 andlocated on holder 50 or may be a separate instrument, or in a thirdpossibility, deployer 60 may be attached to holder 50 intraoperatively.Deployer 60 may have a distal end 62 that interfaces with a proximalportion of deflectable piece 20, in particular in certain preferredembodiments with a segment of implant 10, most likely proximal end 24forming part of proximal segment 40 a of implant 10. When the deployer60 is advanced longitudinally, deployer 60 pushes or moves the proximalend 24, this causes deflection of the deflectable piece 20 to thedeflected state. As seen from FIG. 5A, deployer 60 may be advancedaxially by squeezing or pushing handles 66 located on the holder anddeployer 60. The handles may be fixed on the holder 50 and deployer 60or may be removable. The handle 66 may have a spring component (notshown) to return the handles 66 to their original position aftersqueezing/pushing them to advance the deployer 60.

In certain preferred embodiments, the implant 10 in its final positionmay protrude beyond the vertebrae on the ipsi (proximal to theholder/deployer) and/or contra lateral side.

As shown in FIGS. 1-2, the height of backbone 30 may be at least asgreat as the maximum height of the deflectable piece 20. Typically,backbone 30 may be elongated. Backbone 30 may be a beam, such as a solidbeam or a beam that is mostly solid, or solid except for particularopenings. “Solid” does not preclude being solid with openings. A “beam”is defined to have two dimensions other than its length such that anaverage size of one of those two dimensions is at least 30% of anaverage size of the second of those two dimensions of the beam. As shownin FIG. 8, for example, a straight beam used as backbone 30 may haveanchoring ridges 38 on a top surface 31 and on a bottom surface 34. Thisbeam may be used in motion preservation implants of the presentinvention. The top 31 of the beam 30 (i.e. the backbone 30) may beconfigured to engage cortical bone in the body and receive an impactfrom a load of the cortical bone.

Deflectable piece 20 may have a height, a width and a length. The lengthof deflectable piece 20 may be along a direction of insertion of theimplant and may be by far the largest dimension. In some preferredembodiments, backbone 30 may be configured such that the width of thebackbone (the dimension transverse to the height and transverse to thelength) is at least half as large as a height of the backbone, or inother preferred embodiments at least three-quarters as large as theheight, or between one half and one and a half the height in otherpreferred embodiments. The “height” of the backbone 30 is defined tomean the dimension perpendicular to the plane in which the implant 10device opens. The “width” of the backbone 30 is the dimension transverseto the elongated length of the implant (and is parallel to the axisreferenced herein that runs from the proximal and distal ends of thedeflectable piece and is situated between the backbone and thedeflectable piece). The width of backbone 30 allows it to withstand aload. Although in general backbone 30 may be hollow, solid or partiallyhollow, in preferred embodiments, backbone 30 may be configured to holdat least a majority (or in some other preferred embodiments at leasttwo-thirds or at least three-quarters) of a load held by the implant 10.Implant 10 may be placed under cortical bone (for example the bone of aspinal disc adjacent a vertebral body) and the top surface 31 of thebeam may be configured to engage cortical bone in the body and receivean impact from a load of the cortical bone. Implant 10 may beanatomically shaped to similarly match the contour of the vertebralendplate.

In motion preservation implants 10, the brunt of the necessary impact tocross the annulus to the contralateral aide may be carried by thestraight beam. The beam 30 may take its seat on the annular ring afterproper sizing is performed. Stability of the implant relies on theinitial small aperture in the annulus to allow passage of theimplant—and then the gradual sinking of the ridges 38 along the beam 30into the surrounding tissues. The beam is the most anteriorly locatedpart of the implant 10, mechanically supporting the lordosing effect.Accordingly, the height or the beam may be greater than the height ofthe deflectable piece.

As shown in FIGS. 1-2, backbone 30 may have a window 33 or an opening toallow biocompatible material (such bone graft) to pass into the anteriorarea of the vertebral body, i.e. zone one. Backbone 30 may also have acontoured tip 37 (FIG. 1), for example in the form of a bullet nose, toease insertion of the implant device 10 in between hard tissue (i.e. twoadjacent vertebral bodies). Backbone 30 may also have ridges 38, asshown in FIGS. 3-4 on a surface (for example top surface 31 or a bottomsurface or side surface) that comes into contact with the tissue of thebody in order to prevent movement in an undesired direction. Ridges 38may be in the form of teeth, pyramids, knurls or similar structures.Ridges 38 may be perpendicular to a length of the backbone, as shown inFIGS. 3-4, or the ridges 38 may be parallel to such length, at an angle,in a combination of directions, and may be on all or only part of thesurface. Furthermore, the ridges 38 may vary in height or may be of thesame height, and ridges 38 may be straight or curved.

In a preferred embodiment, there is at least one opening 29 (FIG. 2) inthe sequence 41 of segments 40 to allow access to the at least partiallyenclosed volume in the loop for insertion of biocompatible material suchas bone graft. In a preferred embodiment, the opening 29 is in aproximal segment 40 a or in another segment 40. In other embodiments,opening 29 can be between adjacent segments 40.

Proximal segment 40 a (or in embodiments without segments, proximal end24) may have an interface with pusher component 60 (FIGS. SA-SB) whichallows the segments 40 to be pushed and advanced from the straightconfiguration to the deflected or fully deflected state.

In some preferred embodiments, deflectable piece 20, which may becomprised of the sequence 41 of segments 40, is resiliently biasedtowards the fully deflected state, and as temporarily deformed to theinsertion state. In this case, a guide may maintain deflectable piece 20straight during insertion and removal of the guide then permitsdeflection of the deflectable piece 20, for example by deflection ofsegments 40, to an original shape. In this sense, the deflectable piece20 exhibits elastic memory.

As shown in FIGS. 9-10, which is an end view of the backbone 30 anddeflectable piece 20, a hollow 45 (i.e. a cavity 45) of at least onesegment 40 of the sequence 41 may be cut out to allow axial flexibilityof the implant 10 in response to the repeated impacts of axial loading.The term “axial loading” as used herein means loading in the heightdirection (i.e. perpendicular to the plane in which the implant 10opens). Backbone 30 may also have a hollow cut-out 35, as shown in FIG.9. As also shown in FIGS. 9-10, at least one segment of the sequence mayalso have a lateral cut-out 44 extending to the hollow 45. At least onesegment 40 (and in some preferred embodiments all segments or all exceptone segment) may have a curved exterior. As shown in FIGS. 9-10, the atleast one segment may have an elliptical cross-section at a top, abottom and at least one side of the at least one segment, that is the atleast one segment may have a cross-section that corresponds to anellipse at a top, a bottom and at least one side of the at least onesegment. This may be useful for flexibility for axial loading in thecase of motion preservation implants. In addition, deflectable piece 20,and in particular segments 40, may have curved edges to form a bulletnose shape (i.e. similar to such a shape in backbone 30) in order tocase the deployment of the device 10 in-between hard tissue (for exampletwo adjacent vertebral bodies) in the body.

As shown in FIGS. 12-13, the present invention may also be described asan implant system comprising the implant 10 and further comprising anelongated conduit for inserting said implant in said straightenedinsertion state into the body. A shown in FIG. 21, the present inventionmay also be described as a system 94 comprising the implant 10 andfurther comprising a delivery device such as an injector 83 containingfilling material selected from the group consisting of: biocompatiblematerials, bone grafts, bone chips, bone-growth enhancing agents forinterbody fusion, cement and filling materials for motion preservation.Injector 83 may include a body 83A, a plunger 83B and a cartridge 83C.As shown in the lower depiction of the delivery device 83, injector mayalso include a tip 83D that passes through body 83A and cartridge 83C.Cartridge 83C may be a tube with one end to fit the window 29 of implant10 and the other end to attach to the remainder of device 83. Plunger83B may interface or connect with implant holder 50 (FIG. 6 and FIG. 12)and other delivery instruments. After the cartridge 83C is filled withthe biocompatible material such as bone graft, cartridge 83C may beattached to the body 83A of delivery device 83 at a time when theplunger 83B is in the “back” position. The device is then positioned sothat the distal tip of the cartridge 83C is placed at the deliverywindow 29 of implant 10. The plunger 83B is then advanced so that itpushes the biocompatible material through cartridge 83C and into theimplant 10. The device 83 may then be removed. If additionalbiocompatible material is needed, such material may be inserted intocartridge 83C and the remaining steps repeated as necessary.

As shown in FIGS. 7A-7C, implant 10 may also comprise a lockingarrangement to retain said implant in the pre-defined deflected state orrange and/or to prevent undesired motion between backbone 30 anddeflectable piece 20 (or at least one segment 40 of deflectable piece20). The locking arrangement may include at least one element selectedfrom: cords, cables, strips, hooks, ratchets, interconnections andsnaps. Locking mechanism 70 may be on segments 40. For example, as shownin FIG. 7A, backbone 30 has slots 76A. 763 or other female elements intowhich a one or more teeth 75 (FIG. 7B) mate. Teeth 75 may project from asegment 40, for example on an internal side of segment 40. FIG. 7Cdepicts teeth 75 positioned in an optional second locking position bymating with a second slot 76 b on backbone 30.

Optionally, there may be locking mechanisms between segments to providesegmental interlocking. In embodiments where deflectable piece 20 is notcomprised of separate segments, but rather is comprised of a singleflexible piece of material, deflectable piece 20 may deflect bydeforming reversibly.

As shown in FIG. 15, in certain other embodiment, implant 10 a mayutilize a backbone 30 a that may comprise a flat and relatively thinsegment that may be hingedly interconnected with the sequence ofsegments of the deflectable piece 30 at a distal end of said sequence.In this case, the sequence 41 of segments may be configured to slidinglyinterconnect with said flat segment 30 a at a proximal end 41 a of thesequence of segments 40. FIG. 15 shows the deflectable piece 20 afterlongitudinal pressure has been applied to generate a slidinglongitudinal movement of the sequence 41 relative to the backbone 30 a.

As shown in FIG. 11, in the lumbar vertebral, the area between theanterior and posterior edges of the vertebral body (VB) 80 may bedivided into four equal zones. As shown by the flow chart of FIG. 16,the present invention may be described as a method 100 of implanting animplant 10 into a body. Method 100 may have a step 110 of inserting theimplant into an anterior portion of the body using lateral access whilethe implant is in a straightened or low curvature state, as shown inFIG. 12. The implant may have a backbone 30 and a deflectable piece 20meeting (i.e. interconnected to or abutting) the backbone at a distalend 22 of the deflectable piece. The backbone 30 may be positioned, in apreferred embodiment, on the vertebral lips (apophyseal ring) or withinthe confines of the annulus. The deflectable piece 20 used in thismethod (and other methods) may be comprised of a sequence of segments 40and in general may be structured as described above for implant 10.

Method 100 may also have a step 120 of deploying the implant, forexample posteriorly, by deflecting the deflectable piece, as shown inFIG. 13. For example, step 110 may involve inserting the implant ontozone two of the intervertebral disc and step 120 may involve deployingthe deflectable piece posteriorly onto zone three and/or zone four ofthe intervertebral disc.

The deflecting of deflectable piece 20 may deflect implant 10 into anasymmetric, for example D-shaped, loop by applying longitudinal pressureto the proximal end of the deflectable piece or by applying longitudinalpressure to the backbone 30 to pull the backbone. In either case, thismay generate relative longitudinal movement between the proximal end andat least a distal end of the backbone and may generate an outwardhorizontal movement of at least a portion (for example a centralportion) of the deflectable piece away from the backbone. As shown inFIGS. 12-13, this deflection may be accomplished without a tensioningelement and without a mechanical linkage. For example, as shown in FIG.12-13, the application of longitudinal pressure may be achieved by usinga pusher/deployer to apply longitudinal pressure to a proximal end(which may be a proximal segment) of the deflectable piece afterinsertion. Deflecting the deflectable piece by applying longitudinalpressure to a proximal end of the deflectable piece or to a proximal endof the backbone (for example in an opposite direction for example bypulling the backbone) may generate relative longitudinal movementbetween the proximal end of the deflectable piece 20 and at least adistal end of the backbone and move at least a portion of thedeflectable piece away from the backbone. Furthermore, if deflectablepiece 20 is made up of segments 40 with cut-outs, then deflecting theimplant into an asymmetric loop, such as a D-shaped loop, by applyingthe longitudinal pressure to the proximal end 24 of deflectable piece 20(or to the backbone in an opposite direction) to generate relativelongitudinal movement between the backbone and the proximal end 24 mayclose or partially close cut-outs between segments of a sequence ofsegments of the deflectable piece, as shown in FIGS. 3-4. By setting aninitial position of the backbone the user may be able to pre-define afinal position of the implant in a deflected state.

After deflection, the holder and deployer may be separated and removedfrom the implant in a separate step. The implant device would thenremain between the vertebral body shown in the FIGS. 11-13 and the oneabove it (not shown).

As shown by the flow chart of FIG. 17, the present invention may also bedescribed by a further method 200 of implanting an implant into a body.Method 200 may involve a step 210 of inserting the implant into the bodywhile the implant is in a straightened or tow curvature state, theimplant having a backbone and a deflectable piece, wherein the backbonecomprises a beam. Method 200 may also have a step 220 of anchoring theimplant by situating the backbone 30 on a cortical bone so that thebackbone holds at least a majority of a load of the implant, or in otherpreferred embodiments at least two-thirds of the load. In order toaccomplish this (or for other reasons) method 200 may also involveconfiguring the backbone so that a height of the backbone is at least amaximum height of the deflectable piece. To allow the backbone to carrythe desired load, method 200 may involve configuring the backbone sothat a width of the backbone is at least half as large as a height ofthe backbone, or configuring the backbone so that a width of thebackbone is at least three-quarters as large as a height of thebackbone, or configuring the backbone as a solid beam (or a solid beamwith openings appropriate for delivery of biocompatible material orinstruments). Method 200 (or any of the other methods herein) may alsoinvolve a further step of inserting a biocompatible material into the atleast partially enclosed volume through a window in the implant.

Step 230 may involve guiding the deflectable piece by causing relativelongitudinal movement between a proximal end of the deflectable pieceand the backbone either by holding the backbone stationary whileapplying longitudinal pressure to a proximal end of the deflectablepiece or by pulling the backbone while the deflectable piece isstationary or by closing a telescoping backbone. This may deflect thedeflectable piece such that the deflectable piece together with thebackbone form an asymmetric loop, for example a D-shaped loop, theasymmetric loop defining an at least partially enclosed volume.

As shown by the flow chart of FIG. 18, the present invention may also bedescribed as a further method 300 of implanting an implant into a body.Method 300 may include a step 310 of inserting the implant into aportion of the body while the implant is in a straightened or lowcurvature state, the implant having a backbone and a deflectable piece,for example comprising a sequence of segments interconnected ateffective hinges. A further step 320 may involve having a distal end(for example a distal segment) of the sequence meet the backbone (i.e.by abutting or being interconnected to the backbone) at a distal end ofthe deflectable piece. This may occur prior to insertion (with thebackbone or after insertion of the implant. A further step 330 mayinvolve deploying the implant so as to form a loop between the backboneand deflectable piece together by deflecting the deflectable piece suchthat a proximal end of the deflectable piece moves longitudinally,relative to at least a distal end of the backbone (by either applyinglongitudinal pressure to the proximal end, for example while holding thebackbone stationary, or by pulling the backbone for example whileholding the proximal end 24 stationary or for example by closing atelescoping backbone). The proximal end may also interconnect to thebackbone.

In some preferred embodiments, method 300 may also have a step ofinserting the implant onto an intervertebral disc using lateral accessto the disc and then deploying the implant posteriorly if the implantwas inserted onto an anterior portion of the disc and anteriorly if theimplant was inserted onto the posterior portion of the disc. It Shouldbe fully understood, however, that in other preferred embodiments, anapproach other than lateral access may be used to insert the implantinto the body.

Method 300 may also have a step of locking the implant to preventundesired motion of the deflectable piece relative to the backbone.Another step of method 300 may be applying longitudinal pressure to aproximal segment of a sequence of segments comprising the deflectablepiece so as to deflect the deflectable piece such that the deflectablepiece together with the backbone form an asymmetric loop such asD-shaped loop, the asymmetric loop defining an at least partiallyenclosed volume. Method 300 may involve a step of configuring thebackbone so that a width of the backbone is at least half as large as aheight of the backbone, or in other preferred embodiments at leasttwo-thirds as large, at least three-quarters as large, at least equalto, or between half and one and a half the height. Method 300 may alsoinvolve deploying the implant while the backbone is maintainedstationary along an axis defined by a direction of insertion.

As shown by the flow chart of FIG. 19 and the device shown in FIG. 22,the present invention may also be described as a method 400 ofimplanting implants into a body. Method 400 may have a step 410 ofinserting into the body a first laterally deflectable implant that has afirst backbone and a first deflectable piece while the first deflectablepiece is in a straightened or low curvature insertion state. A furtherstep 420 may be inserting into the body a second laterally deflectableimplant that has a second backbone and a second deflectable piece whilethe second deflectable piece is in a straightened or low curvatureinsertion state and such that the first and second backbones are betweenthe first and second deflectable pieces. In a preferred embodiment, thesecond laterally deflectable implant is inserted into the body such thatthe first backbone and the second backbone are substantially parallel.“Substantially parallel” is defined to mean parallel or within 20rotational degrees of being perfectly parallel. In a preferredembodiment, the first and second backbones are within five rotationaldegrees (or ten rotational degrees or fifteen rotational degrees inother preferred embodiments) of being perfectly parallel. In a preferredembodiment, the inserting of the first and second laterally deflectableimplants in the body may be implemented so that the first and secondbackbones are between the first and second deflectable pieces, as shownin FIG. 22.

Method 400 may also involve a step 430 of deflecting the first andsecond laterally deflectable implants in opposite directions such thatthe first laterally deflectable implant defines a first asymmetric loop(which may be D-shaped), said first asymmetric loop defines an at leastpartially enclosed volume and such that the second laterally deflectableimplant defines a second asymmetric loop (which may be D-shaped), saidsecond asymmetric loop defines an at least partially enclosed volume. Inone preferred embodiment, the shapes of the first and second asymmetricloops are the same (i.e. D-shaped and V-shaped, rectangular andrectangular, etc.) although in other preferred embodiments, one can beD-shaped and the other rectangular or another asymmetric shape.

A further stop of method 400 may be generating relative longitudinalmovement between at least a distal end of the first backbone and aproximal end of the first deflectable piece to deflect the firstdeflectable piece and generating relative longitudinal movement betweenat least a distal end of the second backbone and a proximal end of thesecond deflectable piece to deflect the second deflectable piece.

Method 400 may be useful for two implants inserted in parallel fashionthrough a PLIF, as shown in FIG. 22B.

Furthermore, as shown by the flow chart of FIG. 20 and the device shownin FIGS. 23A-B, the present invention may also be described as a method500 of distracting intervertebral apace 73 between discs or between afirst and a second vertebrae 81, 82. Method 500 may have a step 510 ofinserting an implant 10 structured as described herein into a body whilethe implant 10 is in a straightened or low curvature state, the implanthaving a backbone 30 and a deflectable piece 20 meeting the backbone(interconnected or abutting).

In other preferred embodiments, instead of inserting implant 10, step510 may involve inserting an instrument assembly including an elementhaving the structure of implant 10 (although by right it is not calledan implant since it is not implanted into the body but rather insertedand removed), together with an integrally formed deployer and a holder.This instrument assembly would be removed after distraction is performedand its purpose may have been merely to assess the size of a possibledistraction involving an implant.

Method 500 may have a further step 520 of generating relativelongitudinal movement between a proximal end of the deflectable pieceand at least a distal end of the backbone so as to deflect thedeflectable piece and distract an intervertebral space between the firstand second vertebrae (i.e. between adjacent first and second vertebrae).

Method 500 may also have a step of inserting the implant into the bodysuch that the backbone of the implant is abutting or facing an endplateof one vertebra (of the first and second vertebra) and the deflectablepiece is abutting or facing an endplate of another vertebra (of thefirst and second vertebrae). This may be implemented by for exampleinserting the implant 10 vertically into a vertebral body that hascollapsed and the using step 520 to generate relative longitudinalmovement between a proximal end of the deflectable piece and at least adistal end of the backbone so as to deflect the deflectable piece anddistract endplates of the same vertebra (such as to restore vertebralheight in VCF). For example, prior to inserting the implant, the implantmay be configured so that upon insertion the implant is already orientedvertically such that the backbone is abutting or facing an endplate ofone vertebra and the deflectable piece is abutting or facing an endplateof a second vertebra.

The relative longitudinal movement may be generated using application oflongitudinal pressure, for example against the proximal end 24 oragainst the backbone, for example as described herein, or using anothermethod described herein. In a preferred embodiment of method 500, thedeflecting of the deflectable piece is such that the backbone togetherwith the deflectable piece defines an asymmetric loop, the asymmetricloop defining an at least partially enclosed loop.

The deflectable piece of the implant may be deflected in any of themanners that are described herein.

In order to distract the intervertebral space (i.e. increase thedistance) between the first and second vertebra, since the implant 600is oriented vertically, in some preferred embodiments as shown in FIGS.26A-D, the deflectable piece may incorporate side panels 621 to helpdefine the at least partially enclosed volume. Side panels 621 mayextend from deflectable piece 620 (for example from a middle segment orfrom a segment that is not a first or last segment of deflectable piece620) to backbone 630 and may overlap with the backbone 630 to form acontinuous enclosure for the at least partially enclosed volume. In FIG.26C, the side panels 621 may overlap the sides 631, 634 of backbone 630(which sides in the horizontal orientation of implant 10 are referred toas the top surface 31 and bottom surface 34 of backbone 30) whereas inthe deflected configuration shown in FIG. 268 the side panels 621 mayoverlap only a portion (in the vertical dimension for example betweenvertebra) of sides 631, 634 of backbone 30. This is sufficient to formthe at least partially enclosed volume, and in particular to form ahollow chamber defined by the backbone and by the deflectable piece or aportion (for example a middle segment) of the deflectable piece.Accordingly, after deflection of the deflectable piece, backbone 630 ofimplant 600 may be abutting or facing an endplate of one vertebra of thefirst and second vertebra and deflectable piece 620 may be abutting orfacing an endplate of another vertebra of the first and second vertebra.Furthermore, backbone 630 and deflectable piece 620 together may form,after deflection of the deflectable piece, a chamber that is enclosedother than on a surface facing an endplate of one vertebra of the firstand second vertebra and other than on a surface facing an endplate ofanother vertebra of the first and second vertebra. In contrast to thisembodiment, note that in the horizontally oriented embodiments ofimplant 10 the “sides” of the implant 10 are normally covered by theendplates or other bodily material of the body of the subject.

An opening in a surface of the deflectable piece and an opening in asurface of the backbone may define an unobstructed path between thedeflectable piece and backbone through the at least partially enclosedvolume. For example, as can be seen from FIGS. 26A-D, there may be anunobstructed or direct path from an opening 623 in u top surface 625 ofa middle segment 40 b of deflectable piece 20 to an opening in a bottomsurface of backbone 30. This direct path or passage is useful wherefusion is employed since it may allow fusion of bone or otherbiocompatible material with endplates of adjacent vertebrae. Forclarity, it is noted that the bottom surface of backbone 630 would becalled the rear surface in embodiments showing the implant 10 in ahorizontal orientation. In addition, “top” surface 625 is called “top”by reference to the vertical orientation shown in FIGS. 26A-D yet itcorresponds to side surface 25 of middle segment 40 b in the implant 10of FIG. 2 which depicts an implant 10 in the horizontal orientation.

It is emphasized that FIGS. 26A-D happen to show the vertically orientedimplant with the side panels in the context of a telescoping backbone630 and a deflectable piece 620 having three segments, 640 a, 640 b, 640c, but none of these features (that the backbone 630 is telescoping,that the deflectable piece 620 is segmented and that the deflectablepiece 620 has three segments rather than two, four, five, etc.) arerequired aspects of this embodiment. If for example deflectable piece630 is segmented, the opening in the top surface of deflectable piece630 would normally be in the top surface of a segment other than thefirst and last segment, although this is not a required limitationeither. Furthermore, the vertically oriented embodiment of the implantmay define a loop that is not a strict loop as defined herein (i.e. mayhave a gap) and may incorporate any other suitable feature described inthe context of other embodiments.

As shown in FIG. 26A, moreover, a first segment 640 a may have a hole629 for insertion of biocompatible material such as bone graft,autograft, allograft, etc. Furthermore, as shown in FIGS. 26C-D, the twotelescoping portions 688 a, 688 b of the telescoping backbone 630 mayhave one or more holes 689 and/or threading to interface with a holder650 and/or deployer 660 mechanism or instrument such as described hereinwith respect to implant 10 (see FIGS. 5A-6).

In a still further method of the present invention shown in FIGS. 24C-E,in which deflectable piece 20 is comprised of at least four segments 40,the deflection of deflectable piece 20 may occur separately with respectto two sequences 41 of segments 40. As shown in FIG. 24C, implant anddeflectable piece 20 are initially straight, for example for insertion.As shown in FIG. 24D, the two most proximal segments 40 a, 40 b forminga first sequence 41 of segments 40 are then deflected, for example byactuating the telescoping feature of backbone 30 (or in other preferredembodiments by applying longitudinal pressure to a proximal end 40 cc(see FIG. 2) of segment 40 c or possibly by pulling backbone 30). Moredistal segments 40 c, 40 d remain straight. As shown in FIG. 24E,deflection of segments 40 c, 40 d forming a second sequence 41 ofsegments 40 may then be effectuated by applying longitudinal pressure oractuating the telescoping feature. In the implant depicted in FIGS.24C-E, backbone 30 is telescoping and is of adjustable length. Hence,the deflection may be generated by application of longitudinal pressure,such as against a proximal end 32 of backbone 30 or by an internalmechanism of backbone 30 that actuates the telescoping of backbone 30.

FIGS. 24A-B are similar to FIGS. 24C-E except that in FIGS. 24A-B, eachsequence 41 of segments of the deflectable piece 20 has threeinterconnected segments rather than two. In addition, the telescoping ofthe backbone 30 in FIGS. 24A-B of each sequence may derive from a commonactuator deflecting simultaneously or may be actuated and deflectedseparately whereas in FIGS. 24C-E, the deflection of the separatesequences 41 are necessarily occurring separately.

As shown by FIGS. 27A-K, the present invention may also involve a methodof implanting an implant comprising inserting a holder shaft 92 into animplant 10 of the kind shown in FIGS. 27A-K. The method may also have astep of attaching a deployment tube 91 to the rear of the rotatableelement (i.e. the threaded tube 93). A further step may involvedeflecting the implant by actuating (i.e. rotating) the deployment tube91 so as to rotate the rotatable element 93, thereby advancing therotatable element longitudinally/axially relative to the annular element(i.e. threaded nut). Since the rotatable element is attached to (orabutting) the proximal part of the deflectable piece, the deflectablepiece may move longitudinally relative to at least a distal end of thebackbone. In another step, after deflection of the implant 10, the usermay then disconnect the deployment tube 91. The user may also thendisconnect the holder shaft 92.

It should be understood that one or more steps of the methods describedherein may be combined. Furthermore, any suitable embodiment of implant10 described herein consistent with the steps of a particular method maybe used in any such method. It should also be understood that the term“backbone” 30 used as an element of the implant 10 is not related inmeaning to the “backbone” of a spine of a person into which such animplant may, in some embodiments, be implanted.

As noted, in general the methods and apparatus of the present inventionare not limited to insertion of the implant through lateral access intothe body, and other insertion routes may be used, for example throughthe back as in posterior lumbar interbody fusion (PLIF) ortransforaminal lumbar interbody fusion (TLIF). Furthermore, the term“laterally” in the phrase “laterally deflectable implant” has noconnection or relation with the route of insertion such as insertionthrough “lateral” access. In fact, the direction of the lateral accessis along the direction of insertion of the implant and this direction isconsidered to be longitudinal as discussed herein. Rather. “laterallydeflectable” refers to a direction of the deflection of the deflectablepiece 20 and imposes no limitation as to whether the implant deflects inthe horizontal or vertical orientation.

Furthermore, the terms “vertical” and “vertically” as used herein referto the orientation in either a sagittal plane, a plane parallel to thesagittal plane, a frontal/coronal plane or a plane parallel to thefrontal/coronal plane (the exception being the term “vertical sectionalview” in the Brief Description of the Drawings which has its ordinarymeaning in relation to the view of the implant or other structure). Theterms “horizontal orientation”, “horizontally oriented”, in contrast,refer to horizontal or transverse planes perpendicular to the“vertical”, as used herein. Accordingly, this patent applicationdescribes an implant that may be deflectable in the horizontalorientation but may also be deflectable in the vertical orientation forexample when used for vertical distraction.

While the invention has been described with respect to a limited numberof embodiments, it will be appreciated that many variations,modifications and other applications of the invention may be made.Therefore, the claimed invention as recited in the claims that follow isnot limited to the embodiments described herein.

1. An expanding implant for insertion between two regions of tissue, theimplant comprising: a base having a contact surface for contacting afirst region of tissue, said base comprising a proximal portion havingsaid contact surface and a distal portion having said contact surfaceinterconnected so as to undergo linear relative motion, said baseassuming an initial length and being shortened towards a second lengthby linear relative motion of said proximal portion towards said distalportion, and wherein said base is configured not to deflect whenundergoing the linear relative motion; a deflectable piece having afirst rigid linking segment, a second rigid linking segment, and anintermediate portion, wherein said deflectable piece in a fullydeflected state defines, together with said base, an asymmetric loop,and wherein said asymmetric loop defines an a least partially enclosedvolume; said first rigid linking segment hingedly connected to a distalregion of said distal portion of said base for relative rotation about asingle pivot axis relative to said distal portion of the base; saidsecond rigid linking segment hingedly connected to a proximal region ofsaid proximal portion of said base; and said intermediate portion havinga contact surface for contacting a second region of tissue, said contactsurface of said intermediate portion spanning a majority of said secondlength, said intermediate portion being hingedly connected to said firstlinking segment and to said second linking segment such that shorteningof said base from said initial length towards said second length causesan increase in a distance between said contact surface of said base andsaid intermediate portion and deflects said deflectable piece to saidfully deflected state without deflecting said base to form, with saidbase, the asymmetric loop.
 2. The expanding implant of claim 1, whereinsaid intermediate portion is implemented as a rigid intermediatesegment.
 3. The expanding implant of claim 2, wherein said intermediatesegment and said base are formed with regions of overlap, and whereinsaid regions of overlap are sufficient to maintain overlap between saidintermediate segment and said base during said increase in distancebetween said contact surfaces.
 4. The expanding implant of claim 2,wherein at least one of said second linking segment and said proximalportion of said base is formed with an aperture to allow insertion offilling material into the implant along a direction of elongation of theimplant.
 5. The expanding implant of claim 1, wherein at least one ofsaid second linking segment and said proximal portion of said base isformed with an aperture to allow insertion of filling material into theimplant along a direction of elongation of the implant.
 6. The expandingimplant of claim 1, further comprising: (a) a shaft engagable with saiddistal portion of said base and extending along said base so as toproject from the implant in a proximal direction; and (b) a deploymentelement cooperating with the proximal portion of said base, whereinadvancing of said deployment element relative to said shaft is effectiveto deploy said proximal portion of said base towards said distal portionof said base.
 7. The expanding implant of claim 6, wherein saiddeployment element is implemented as a tube enclosing a proximal portionof said shaft.
 8. The expanding implant of claim 7, wherein said tube isin threaded engagement with said proximal portion of said shaft suchthat rotation of said deployment tube relative to said shaft iseffective to advance said tube, thereby displacing said proximal portionof said base towards said distal portion of said base.
 9. The expandingimplant of claim 1, further comprising a locking arrangement deployed toretain a shortened state of said base, thereby maintaining an expandedstate of the implant.
 10. The expanding implant of claim 1, wherein saidcontact surfaces of said base and said intermediate portion aresubstantially parallel.
 11. The expanding implant of claim 1, whereinsaid intermediate portion and said base each define one or more openingstherethrough such that said one or more openings provide at least oneunobstructed path between the first and second regions of tissue.
 12. Anexpanding implant for insertion between two regions of tissue, theimplant comprising: a base having a contact surface for contacting afirst region of tissue, said base comprising a proximal portion insliding engagement with a distal portion, said base assuming an initiallength and being shortened towards a second length when said proximalportion slides towards said distal portion; a first rigid linkingsegment having a first end and an opposing second end, wherein saidfirst end is hingedly connected to a distal region of said distalportion of said base; a second rigid linking segment having a first endand an opposing second end, wherein said first end is hingedly connectedto a proximal region of said proximal portion of said base; and anintermediate portion having a first end and an opposing second end, andsaid intermediate portion having a contact surface for contacting asecond region of tissue, said contact surface of said intermediateportion spanning a majority of said second length, said first end ofsaid intermediate portion being hingedly connected to said second end ofsaid first linking segment and said second end of said intermediateportion being hingedly connected to said second end of said secondlinking segment such that shortening of said base from said initiallength towards said second length causes an increase in a distancebetween said contact surfaces of said base and said intermediate portionand deflects said first rigid linking segment, said second rigid linkingsegment, and said intermediate portion to a fully deflected statewithout deflecting said base to form, with said base, an asymmetric loopdefining an a least partially enclosed volume.
 13. The expanding implantof claim 12, wherein said intermediate portion and said base each defineone or more openings therethrough such that said one or more openingsprovide at least one unobstructed path between the first and secondregions of tissue.
 14. The expanding implant of claim 12, wherein saidasymmetric loop is D-shaped.
 15. The expanding implant of claim 12,wherein said intermediate portion and said base are formed with regionsof overlap, and wherein said regions of overlap are sufficient tomaintain overlap between said intermediate portion and said base duringsaid increase in distance between said contact surfaces.
 16. Anexpanding implant for insertion between two regions of tissue, theimplant comprising: a base having a contact surface for contacting afirst region of tissue, said base comprising a proximal portion insliding engagement with a distal portion, said base assuming an initiallength and being shortened towards a second length when said proximalportion slides towards said distal portion; a first rigid linkingsegment having a first end and an opposing second end, wherein saidfirst end is hingedly connected directly to a distal region of saiddistal portion of said base; a second rigid linking segment having afirst end and an opposing second end, wherein said first end is hingedlyconnected directly to a proximal region of said proximal portion of saidbase; and an intermediate portion having a first end and an opposingsecond end, and said intermediate portion having a contact surface forcontacting a second region of tissue, said contact surface of saidintermediate portion spanning a majority of said second length, saidfirst end of said intermediate portion being hingedly connected directlyto said second end of said first linking segment and said second end ofsaid intermediate portion being hingedly connected directly to saidsecond end of said second linking segment such that shortening of saidbase from said initial length towards said second length causes anincrease in a distance between said contact surfaces of said base andsaid intermediate portion and deflects said first rigid linking segment,said second rigid linking segment, and said intermediate portion to afully deflected state without deflecting said base.
 17. The expandingimplant of claim 16, wherein at least one of said base, said secondrigid linking segment, said first rigid linking segment, and saidintermediate portion includes one or more openings.
 18. The expandingimplant of claim 16, wherein when in an expanded state said implantforms an asymmetric D-shaped loop defining an a least partially enclosedvolume.
 19. The expanding implant of claim 16, further comprising alocking arrangement deployed to retain a shortened state of said base,thereby maintaining an expanded state of the implant.
 20. The expandingimplant of claim 16, wherein when the implant is in an expanded statethe said contact surfaces of said base and said intermediate portion aresubstantially parallel and each of said first rigid linking segment andsaid second rigid linking segment are angled relative to said base.